This July, the Drip Port will turn three years old. If the port were a human baby, it would now be walking, talking, learning, and beginning to read (as well as drooling). However, as much as Brian coddles it, the Drip Port isn't a baby. It's a small collection of long-term investments in American businesses.

The first year of Drip Port's life was busiest. We began to acquire stakes in three companies in less than one year, and we bought shares in all four of our initial holdings in just one year and two months. For the past twenty months since then, however, we have not initiated any purchases of any new companies.

So, for nearly two years, we have done nothing new.

This may seem odd given that we're still in the building stage of our young portfolio's life, and given that we're constantly trying to find new 20-year investments. We studied oil and gas companies for over six months, and we studied food and beverage companies for another ten months (a study that continues today), but we have foregone any new purchases.

And that's just fine! Often, the best thing that you can do as an investor is... drumroll, please... absolutely nothing! Assuming that your long-term savings is being invested in an index fund or in a company or two that you know well and love, there is no reason to rush prematurely into new investments.

A limited number of superb companies exist in the world, and there is a limited number of great buying opportunities (regarding valuation) when you're targeting well-recognized, decades-old (or century-old!) companies. We are not likely to see mind-blowing valuation opportunities on such companies anytime soon, so we're just looking for "good" opportunities. Even though it is a short-term measure, over the past three years, Coca-Cola (NYSE: KO) at 55 times earnings wasn't the ticket to good opportunity. Campbell Soup(NYSE: CPB) at 40 times earnings wasn't either! (Oops! We paid a price.)

So what is a good opportunity right now?

In our search for excellent quality businesses at good prices, Brian and I have looked at more than 35 public businesses in the last two years. While smoking king-size cigars in Fool HQ on Thursday evening, we chatted about our past two years (I'm kidding about the cigars) and Brian pointed out that most of the stocks that we considered since 1998 have not gained ground since we considered them. Most have actually declined. This is especially true of food and beverage companies.

That said, we're still interested in this industry as a long-term investment. Why? For one, the industry is at least predictable in a macro sense: people will always need food and drink. Food is not an optional purchase for anyone. It is a must. Secondly, the food industry is predictable in that product prices typically follow inflation, and some companies also have reliable pricing power.

In fact, we want to actively invest in a leading food and beverage company for many of the same reasons that we invest in healthcare and financial services. Namely, these industries are relatively predictable over a long period -- it is nearly certain that consumer needs in these spaces will not wane over time, but grow. We invested in the computer CPU industry for similar reasons: Over 20 years, demand is likely to rise several-fold, while production expenses are bound to shrink, and leading companies (namely Intel with 80% market share) are likely to become more valuable provided they have strong management.

In our Drip Portfolio, we want to be diversified, but we still only invest in industries that we understand. With healthcare, financial services, technology (CPUs), and food and beverages, we own and understand our stakes in very important industries -- industries that will never disappear. Unfortunately, our current food investment is dead in the water and we won't buy more Campbell because its Drip fees are so high. Fortunately, however, we are now close to a buy decision for our new food and beverage investment. Our two finalists are Wrigley (NYSE: WWY) and PepsiCo(NYSE: PEP).

Soon, we'll have much more to say and a decision!

To close, the reminder for today is to take your time when investing. Don't rush to diversify into companies or industries (such as oil and gas, for us) that you don't completely understand and that, if your needs are like our own, you can't reasonably project a general outcome for over 10 years or longer.

To read Drip columns from the past week, please see the links below. To discuss Drip Port and investing in Drips, visit the discussion boards linked below. Have a great weekend and Fool on!

dividend adjusted. Dividends have been added to the total return of the index.

NoteDrip Port launched with $500 on July 28, 1997, adds $100 to invest every month, and the goal is to own $150,000 in stock by August of the year 2017. Due to the slow nature of dollar-cost-averaging and our relatively significant starting costs, we do not expect to seriously challenge the S&P 500 for the first three to five years as we build an investment base. The long-term advantages of dollar-cost-averaging still overcome the short-term disadvantages, however. Final note: our investment in Campbell Soup is frozen due to fees instituted in its investment plan. Click here for a history of all Drip Port transactions.